System and method for separating competing anions from per- and polyfluoroalkyl substances (pfas) in a flow of water

Abstract

A system for separating competing anions from per- and polyfluoroalkyl substances (PFAS) in a flow of water contaminated with PFAS and elevated levels of competing anions that includes a separation subsystem which receives the flow of water contaminated with PFAS and elevated levels of competing anions and separates competing anions from the PFAS and concentrates the PFAS to produce a treated flow of water having separated competing anions therein and a flow of water having a majority of PFAS therein. At least one anion exchange vessel having an anion exchange resin therein receives the flow of water having a majority of PFAS therein and removes PFAS from the water to produce a flow of treated water having a majority of the PFAS removed. The separation of competing anions by the separation subsystem increases the treatment capacity of the anion exchange resin to remove PFAS from the contaminated water.

What is claimed is: 
     
         1 . A method for separating competing anions from per- and polyfluoroalkyl substances (PFAS) in a flow of water contaminated with PFAS and elevated levels of competing anions, the method comprising:
 receiving the flow of water contaminated with PFAS and elevated levels of competing anions;   separating competing anions from the PFAS and concentrating the PFAS to produce a treated flow of water having separated competing anions therein and a flow of water having a majority of the PFAS therein;   receiving the flow of water having a majority of the PFAS therein;   removing PFAS from the flow of water having a majority of the PFAS therein to produce a flow of treated water having a majority of the PFAS removed; and   wherein the separation of competing anions from the PFAS increases a treatment capacity of an anion exchange resin to remove PFAS from the contaminated water.   
     
     
         2 . The method of  claim 1  in which the anion exchange resin includes a regenerable anion exchange resin. 
     
     
         3 . The method of  claim 1  in which the anion exchange resin includes a single use anion exchange resin. 
     
     
         4 . The method of  claim 1  in which the separating includes membrane separation. 
     
     
         5 . The method of  claim 4  in which the membrane separation includes nanofiltration. 
     
     
         6 . The method of  claim 4  in which the separation includes ultrafiltration. 
     
     
         7 . The method of  claim 1  in which the separating includes foam fractionation. 
     
     
         8 . The method of  claim 7  including increasing the production of microbubbles and foam. 
     
     
         9 . The method of  claim 8  including:
 receiving the flow of water contaminated with PFAS and elevated levels of competing anions, 
 introducing and mixing a gas into a recycled flow of water having separated competing anions therein and generating a two-phase flow of microbubbles and water having separated competing anions therein, and 
 receiving the two-phase flow in a cylindrical baffle and inducing rotational movement that generates intense mixing and turbulence to maximize formation and distribution of the microbubbles and foam. 
 
     
     
         10 . The method of  claim 9  including separating the two-phase flow of microbubbles and water having separated competing anions therein from the treated flow of water having separated competing anions therein. 
     
     
         11 . The method of  claim 7  in which the foam fractionation is configured to produce a concentrated flow of foam that transforms into the flow of water having the majority of the PFAS therein. 
     
     
         12 . The system of  claim 7  in which the foam fractionation includes heating the foam to enhance the transformation of the foam into the flow of water having the majority of PFAS therein. 
     
     
         13 . The method of  claim 1  in which the competing ions include one or more of: chloride, sulfate, nitrate, bicarbonate, and perchlorate. 
     
     
         14 . The method of  claim 1  in which the flow of water contaminated with PFAS and elevated levels of competing anions includes industrial wastewater. 
     
     
         15 . The method of  claim 1  in which the flow of water contaminated with PFAS and elevated levels of competing anions includes landfill leachate. 
     
     
         16 . The method of  claim 1  in which the flow of water contaminated with PFAS and elevated levels of competing anions includes contaminated groundwater. 
     
     
         17 . The method of  claim 1  including adding a supplemental surfactant to increase the productions of microbubbles and foam. 
     
     
         18 . The method of  claim 17  in which the supplemental surfactant includes an anionic, cationic, zwitterionic, nonionic, and/or a protein-based surfactant.